The present invention concerns photometers, i.e. optical analytical instruments that employ optical energy to determine physical parameters of fluids such as liquids or gasses found in effluents and in industrial processes.
There are many instances in which it would be useful to have a relatively low cost analytical instrument that could be depended upon to monitor a process or environmental condition at a desired level of accuracy and which did not require highly trained personnel for its operation and maintenance. There is a special need for a low cost instrument in the case of monitoring waste water and effluent gasses before release to the environment. The present invention addresses these needs, and provides general improvements in photometers as well.